1. Field of the Invention
The present invention relates to a pattern drawing method and a pattern drawing apparatus, for drawing a planar pattern of one of convex or concave portions in a concave/convex pattern for use in manufacturing e.g., an information recording medium, and a stamper manufacturing method using the drawn planar pattern.
2. Description of the Related Art
As this kind of the pattern drawing method, there has been proposed a method of manufacturing a master carrier (master carrier for magnetic transfer) for magnetically transferring a servo pattern or the like to a slave medium in Japanese Laid-Open Patent Publication (Kokai) No. 2003-91806. In this method, when a master carrier is manufactured, first, a drawing process e.g., of a servo pattern is executed. More specifically, a photoresist is spin-coated on a circular plate, such as a glass, to form a photoresist layer (hereinafter also referred to as “the resist layer”). Then, the resist layer is irradiated with an electron beam to thereby draw a servo pattern, for example. In doing this, according to the method, the servo pattern or the like is formed by irradiating the resist layer with an electron beam having an effective drawing diameter smaller than the width of a track, while rotating the circular plate, and thereby dividing a region within which a convex portion of the master carrier, for example, is to be formed (hereinafter referred to as “the formation region”) into a plurality of belt-shaped areas (hereinafter referred to as “the belt-shaped areas”) in the direction of radius of the circular plate.
More specifically, as shown in FIG. 12, the circular plate is rotated in a direction indicated by an arrow R, and when a start position S1 at which irradiation of the electron beam is to be started is positioned under an electron gun, the electron gun is caused to start the irradiation of the electron beam. Then, when a stop position E1 at which irradiation of the electron beam is to be stopped is positioned under the electron gun, the electron gun is caused to stop the irradiation of the electron beam. This completes the irradiation of the electron beam onto a belt-shaped irradiation area A11 indicated by a broken line in FIG. 12. Next, the electron gun is adjusted such that the irradiation position of the electron beam on the circular plate (central position of the irradiated electron beam) is outward of e.g., the belt-shaped irradiation area A11 (rightward of the same as viewed in FIG. 12). Then, when a start position S2 is positioned under the electron gun, irradiation of the electron beam is started, and when a stop position E2 is positioned under the electron gun, the irradiation of the electron beam is stopped. This completes the irradiation of the electron beam onto a belt-shaped irradiation area A12 indicated by a broken line in FIG. 12. Similarly, the electron beam is irradiated onto a belt-shaped irradiation area A13 from a start position S3 to a stop position E3,
Then, the circular plate on which the drawing process is completed is subjected to a development process to thereby form a concave portion (concave/convex pattern) on the resist layer. In this case, e.g., a portion P11 and a portion P12 of the resist layer are irradiated with the electron beam only for a very short time period after the start of irradiation of the electron beam or before the stop of irradiation thereof, and the amount of the electron beam exposure of the portions is small, so that they remain on the disk without being eliminated by the development process. On the other hand, e.g., portions P13 to P15 of the resist layer are eliminated from the circular plate by the development process, since they continue to be irradiated for a longer time period with a sufficient amount of the electron beam exposure. As a result, the resist layer within a formation region A0x indicated by a one-dot chain line in FIG. 12 is eliminated to form a concave portion. Thus a concave/convex pattern is formed on the circular plate. Subsequently, a conductive layer is formed on a surface in which the concave/convex pattern is formed, whereafter an electroforming process is carried out to manufacture a metal substrate. In doing this, the concave/convex pattern formed on the circular plate (resist layer) by the development process is transferred to a metal material to thereby form a convex portion having approximately the same shape in plan view as that of the formation region A0x. After that, a magnetic layer is formed in a manner so as to cover the concave/convex pattern transferred to the substrate, whereby the master carrier is completed.